Toner dispensing apparatus for electrostatic copying machines



G.' M ATKOVICH ET AL 3,504,968 TONER DISPENSING APPARATUS F ORELECTROSTATIC .COPYING MACHINES Filed May 51, 1966 April 7, 1970 2Sheets-Sheet l fi r" u v QN/ H I 8% 1 MW Q w: i m J I III :IIIL 1fl MIAQ \M.) E v 1 W J in Q W M -1.- on $1" if A i NM ma 7, .C m s w Y o n 0m m FM 3 a m I w 1 U W m D d e I M W W21 Z far 680 April7, 1970 G.-MAVTKI OVEICH ETAL 1 3,504,968

TONER DISPENSING APPARATUS FOR ELECTROSTATIC COPYING MACHINES Filed May31, 1966 2 h ts-Sheet 2 INVENTORS Waler J. Hanson FTTOFNEY United StatesPatent 3,504,968 TONER DISPENSING APPARATUS FOR ELECTRO- STATIC COPYINGMACHINES George Matkovich, Stamford, and Walter J. Hanson, OldGreenwich, Conn., assignors to Pitney-Bowes, Inc., Stamford, Conn., acorporation of Delaware Filed May 31, 1966, Ser. No. 553,822 Int. Cl.G03g 9/04, 15/00,]3/00 US. Cl. 355-10 4 Claims ABSTRACT OF THEDISCLOSURE This invention relates generally to electrophotographiccopying machines. More particularly it relates to an apparatus forautomatically replacing toner material which is applied to exposed copypaper during the developing process so as to produce a visible imagewhich is a reproduction of the original sheet.

The present invention is based upon the theory of replacing expendedtoner material at a rate very closely approximating or sustantiallyequal to the rate at which the toner material is removed from adeveloping medium, by exposed copy paper passing therethrough. This isaccomplished, in its broader aspects by correlating the rate of tonerreplenishment with the length of copy paper which is fed through thedeveloping medium, which length may vary from copy to copy, to the endthat the quality of copies produced remains constant over a large numberof copies regardless of the amount of toner material which may beremoved from the developing medium by any individual copy, this amountdepending upon the length of copy paper being fed through the developingmedium for such individual copy and the extent of indicia to bereproduced thereon.

in electrophotographic copying machines of the type to which the presentinvention relates, an original sheet having indicia thereon is insertedinto the copying machine and is illuminated. An image of the indicia onthe original is transferred by means of an optical system to copy paperwhich has previously been uniformly electrostatically charged. Theintensity of the light reflected from the original, in accordance withthe indicia thereon, produces a latent image of the indicia on the copypaper by dissipating the electrostatic charge on the copy paper in thoseareas which are exposed to the reflected light. Thereafter, the copypaper is passed through a developing medium which typically is a liquidbath containing pigmented toner particles held in suspension whichadhere to the remaining electrostatically charged areas of the copypaper to produce a visible image.

Since the quality of the copy, that is the sharpness and clarity ofdetail and the character of shading, is largely dependent upon theextent to which particles of toner material adhere to the charged areasof the copy paper, it is important to maintain a proper balance of tonermaterial in suspension in the developing bath at all times as to obtainconsistently high quality copies. Should the amount of toner material insuspension become too high or too low, the copies becomes too dark ortoo light re- 3,504,968 Patented Apr. 7, 1970 ICC spectively, in eitherof which events sharpness and clarity of detail is lost, shading maybecome distorted, and generally copies are produced which, in varyingdegrees, are unacceptable for the purposes intended.

It is apparent that the need for additional toner material in thedeveloping bath may be ascertained by observation of copies as theyemerge from the copying machine, and that it may be left to thediscretion of the user as to whether it is necessary to add tonermaterial and in what quantity. The obvious guess-work inherent in such aprocedure will inevitably result in a lack of uniformity in the qualityof copies over an extended period of time.

It has therefore been proposed to add toner material automatically tothe developing bath to maintain the proper balance of toner particles insuspension Within permissible limits. One such proposal has been toobserve the concentration of toner particles in suspension byphoto-electric means, and to thereby actuate a dispensing mechanism whenthe concentration of toner material reaches a predetermined minimumlevel to replace toner material until a predetermined maximumconcentration is obtained. While this procedure has been found toaccomplish satisfactory results, the equipment required to carry it outis relatively complicated and expensive and therefore not commerciallyattractive, and it is not suitable for maintenance or adjustment byunskilled persons.

A simpler and less costly proposal has been to automatically dispense apredetermined quantity of toner material into the developing bath eachtime the copying machine is cycled for operation to produce a copy. Adistinct disadvantage of this procedure is that it does not correlatethe rate of toner material replenishment with the rate at which it iswithdrawn from the developing bath. Thus, more or less toner materialmay be withdrawn on each copy in accordance with the extent of indiciaon the original, yet a fixed predetermined quantity of toner material isreplaced with each machine operation producing a copy. It is thereforepossible, and in fact probable, that the rate of toner materialreplacement will be out of synchronism with the rate at which it iswithdrawn, resulting in an eventual imbalance of toner particles insuspension to the extent that unacceptable copies are produced.

The above disadvantage is apparent in copying machines Which utilize cutsheets of a predetermined length on which copies are produced. Thisdisadvantage becomes more critical, however, in those machines in whichcopy paper is supplied as a web in roll form, the length of an originalsheet is measured as it passes through the machine and a length of copypaper is severed from the web which corresponds to the length of theoriginal sheet. In such a machine, it would be completely undesirable todispense a predetermined quantity of toner material each time that thecopying machine is cycled for operation since it would be necessary toadjust the dispensing mechanism to operate in accordance with the lengthof the original sheet each time such length changes. Thus a series ofshort copies would withdraw less toner material with each machine cyclethan would a corresponding series of long copies, yet the same quantityof toner material would be dispensed with each copy produced.

It is, therefore, a principal object of the present inven tion toprovide a toner dispensing apparatus for use in an electrophotographiccopying machine which automatically maintains a proper balance in theconcentration of toner particles in suspension over an extended periodof time and yet avoids the disadvantages of prior art devices.

Another object of the present invention is to provide a toner dispensingapparatus for an electrophotographic copying machine which dispensesadditional toner material into the developing bath at a rate which iscorrelated with the rate at which the toner material is withdrawn fromthe developing bath by copy paper passing therethrough.

Still another object of the present invention is to provide a tonerdispensing apparatus for an electrophotographic copying machine whichdispenses a metered quantity of toner material spaced in accordance withthe feeding of successive predetermined unit lengths of copy paper toand through the developing solution.

It is yet another object of the present invention to provide a tonerdispensing apparatus for an electrophotographic copying machine whichoperates either in response to the feeding of cut sheets of variablepredetermined length, or in response to feeding of variable lengths asdetermined by the length of an original sheet passing through thecopying machine which is measured and according to which a correspondinglength of copy paper is automatically severed from a web thereof.

Yet another object of the present invention is to provide a tonerdispensing apparatus for an electrophotographic copying machine in whichthe amount of toner material dispensed per unit length of copy paperdelivered to the developing bath may be varied so as to maintain therate of toner material replenishment correlated with the rate at whichit is withdrawn from the developing bath regardless of the density ofindicia on a given length of original which is to be reproduced on apredetermined or correspondingly measured length of copy paper.

A still further object of the present invention is to provide a tonerdispensing apparatus for an electrostatic copying machine which isrelatively simple in construction, economical to manufacture, and iseasily maintained by unskilled persons.

In its broader aspects, the principles of the invention are presentlyembodied in a toner dispensing apparatus for use in combination with allelectrophotographic copying machine having means for feeding copy paperof varying lengths along a copy paper path, means for producing avisible image on the copy paper from an original sheet and includingdeveloping means in the copy paper path having toner material therein,the toner dispensing apparatus comprising a source of concentrated tonermaterial, dispensing means having communication with the source of tonermaterial and with the developing means and operable when actuated todispense toner material, and means operable only when the copy paper isbeing fed past a given point in the copy path for actuating thedispensing means to dispense a quantity of toner material metered inaccordance with the feeding of each predetermined unit length of copypaper past the given point in the copy paper path.

The foregoing and other objects and features of the present inventionwill be more readily apparent from an understanding of the followingdetailed description when considered in conjunction with theaccompanying drawings in which:

FIGURE 1 is a side view of a toner dispensing apparatus made inaccordance with the principles of this invention, and shown in operativeassociation with a fragmentary portion of an electrostatic copyingmachine.

FIGURE 2 is an end view, partly in section, of the structure illustratedin FIG. 1,

FIGURE 3 is a plan view of the structure illustrated in FIGS. 1 and 2,'

FIGURE 4 is a view, on an enlarged scale, of a portion of the drivemeans, taken on the line 44 of FIG. 1, and

FIGURE 5 is a schematic view of certain operative details of a copyingmachine with which the present invention is concerned.

Referring to the drawings, and particularly to FIGS. 1 and 2 thereof,the toner dispensing apparatus of this invention is illustrated asassociated with an electrostatic copying machine, only so much of thestructure of the copying machine being shown as is necessary to anunderstanding of the principles of the invention.

The numeral 10 designates generally an electrostatic copying machinecomprising a base 12, a pair of upright parallel side frame members 14and 16, and a suitable housing 18 enclosing the copying machine as awhole. A developing tank 20 containing a suitable quantity of liquiddeveloping solution 22 is mounted within the copying machine 10, and isillustratively shown as resting on the base 12. The developing solution22 contains toner particles in suspension which are withdrawn from thesolution by exposed copy paper passing therethrough. The exposed copypaper is guided through the developing bath 22 by suitable guides andfeed rollers, hereinafter more fully described, the rollers being drivenby an endless chain 24 disposed outside of the frame member 16.

It will be apparent to those skilled in the art that the specificconstruction of the copying machine forms no part of the presentinvention and is, therefore, not disclosed in detail, with the exceptionof the hereinafter described structure thereof with which the tonerdispensing apparatus cooperates to control operation of the latter inresponse to operation of the former.

The dispensing apparatus comprises a container 26 suitably mounted inthe copying machine, such as by being suspended from a plate 28 having aslot 30 therein which receives the neck of the container 26 (see FIG.3). The mouth of the container is closed by a cap 32 which has a pump 34mounted therein, the pump 34 having com munication with the containercontents by means of the dip tube 36. The pump 34 is provided with anactuating stem 38 projecting upwardly thereform and a discharge spout 40projecting laterally from the stem 38. The spout 40 is in communicationwith a tube 42 secured to the frame member 16 by suitable clamps 44, thetube 42 extending downwardly and terminating in position to dischargeinto the developing solution tank 20.

The pump 34 is preferably though not necessarily a positive displacementtype reciprocating pump in which a pump chamber 46 communicates with thedip tube 36 through a one-way ball valve 47, and the stem 38 isintegrally formed with a hollow piston 48 having another one-way ballvalve therein (not shown) which reciprocates telescopically within thepump chamber 46 and carries the other ball valve therewith, the pistonbeing normally urged upwardly by a spring 49 within the pump chamber.Once the pump is initially primed, a downward movement of the piston 48and stem 38 forces a metered quantity of fluid in the pump chamber 34 toflow into the hollow piston through the ball valve not shown which, inturn, forces liquid in the piston to be discharged through the spout 40.On the return stroke of the piston, additional liquid is drawn up thedip tube past the ball valve 47 to replace the quantity discharged.

The pump 34 is actuated by an actuating mechanism comprising a lever 50fixedly mounted on a shaft 52 which is iournaled for rotation in theside frame members 14 and 16. An extension 54 of the shaft 52 projectsoutwardly of the side frame member 14 and fixedly carries a second lever56 on the free end of which is mounted a cam follower or roller 58. Acam 60 having a lobed portion 62 and a sharp declining face 64 issecured to, or formed integrally with, a gear 66 which is mounted forrotation on the frame member 14 as by the stub shaft 68. The roller 58is continuously urged into contact with the cam 60 by a spring connectedbetween the stub shaft 68 and the lever 56. The spring 70 has sufficientstrength to overcome the compression spring 49 located in the pump 34 sothat during the major portion of rotation of the cam 60, the pump stem38 and associated parts are maintained in a depressed position, i.e.,the position occupied by the parts at the end of a dispensing stroke.

It will thus be seen that the actuating mechanism constitutes acylindrically operable means for periodically actuating the pump 34 todispense a metered quantity of toner material each time the cam 60 makesone complete revolution.

While it would be entirely feasible to provide an independent drivemeans for the gear 66 which would be operable only when copy paper isbeing fed past a given point in the copy paper path, it has been foundto be more expedient to drive the gear 66 directly from a feedingmechanism which is operable only to feed and while feeding a variablelength of copy paper. Thus, the copying machine includes a means forfeeding copy paper of variable lengths along a copy paper path whethermanually settable to feed a selected predetermined length cut sheets, orautomatically operated to feed a variably length of copy paper severedfrom a web there-of in accordance with a measured length of the originalsheet. This means includes the above mentioned feeding mechanism towhich the gear 66 is directly connected.

More particularly, a pair of feed rollers 72 and 74 are carried byshafts 76 and 78 respectively, which are journaled for rotation in theside frame members 14 and 16. Roller 72 is driven by means hereinafterdescribed, and by means of gears 80 and 82 mounted on shafts 76 and 78respectively outside of the frame member 14, the roller 72 drives theroller 74. As best seen in FIGS. 3 and 4, the gear 80 meshes with boththe upper roller gear 82 and with the cam gear 66 whereby both of thelatter are simultaneously driven in response to rotation of the roller72.

The latter is driven by means of a gear 84 mounted on the shaft 76outside of the opposite side frame member 16. This gear in turn isdriven by a gear 86 connected to a shaft 88 rotatably mounted on one endof a lever 90, the lever 90 being pivotably supported on the framemember 16 by a stud 92. The' shaft 88 also carries a sprocket wheel 94continuously engaged by the drive chain 24 so that both the sprocket 94and gear 86 rotate in response to movement of the chain 24 when thegears 84 and 86 aare engaged.

In order to start and stop the feed rollers 72 and 74 as well as the camgear 66 for the dispensing mechanism in synchronism with the determinatelength of copy paper to be fed to the developing bath, the lever 90,which is pivotably mounted on the stud 92, is connected at its oppositeend to the armature 96 of a solenoid 98. As best seen in FIG. 1, aspring 100 is connected between the upper end of the lever 90 and a pin102 mounted on the side frame member 16 to normally urge the lever 90 toa position in which the gear 86 is out of contact with the gear 84 sothat the feed rollers 72 and 74 and the cam gear are stationary. Uponenergization of the solenoid 98, the armature 96 is moved toward theleft as viewed in FIG. 1, whereupon the lever 90 is rocked in acounterclockwise direction to engage the gear 86 with the gear 84 'toestablish a driving relationship between the chain 24 tand the feedrollers 72 and 74 and the cam gear 66. The lever 90 and gears 86 and 84thus constitute a clutch actuated by the solenoid 98 and the spring 100.Thus it is seen that the cam gear 66 and associated parts driven therebyconstitute a means which is operable or driven only when copy paper isbeing fed past a given point in the copy paper path for periodicallyactuating the dispensing means to dispense a metered quantity of tonermaterial spaced in accordance with the feeding of each predeterminedunit length of copy paper past the given point.

As briefly indicated above, the means for feeding a varying length ofcopy paper, of which the rollers 72 and 74, are a part, further includeseither manually settable means for feeding a selected predeterminedlength cut sheet, or automatic sensing and severing means for feeding avariable length of copy paper severed from a web in accordance with ameasured length of original sheet from which the copy is made. The tonerdispensing apparatus of the present invention is at present preferablyutilized in connection with a copying machine of the latter type, and isdiagrammatically illustrated in FIG. in operative association with onlyso much of such a copying machine as is necessary to understand theinvention.

Accordingly, referring to FIG. 5, the endless chain 24 is disclosed ascontinuously engaging several pairs of feed roller pairs 102, 104 and106 constituting, with suitable guides,- a copy paper path and transfermeans for conveying determinate lengths of copy paper to and through thedeveloping tank 20 and to a suitable receiver for finished copies.Additional roller pairs 110 and 112 constitute, also with'suitableguides, an original sheet transfer means for conveying the originalsheet to and through an illuminating station (not shown). The chain 24is driven by a motor 114 and a sprocket 116 thereby driving the copypaper roller pairs and original sheet roller pairs in unison.

A severing mechanism generally indicated by the numeral 118 is disposedbetween the roller pair 102 and the feed rollers 72 and 74, the severingmechanism including a solenoid 120 or other suitable power means foractuating the severing mechanism at an appropriate instant.

A sensing element, such as the micro-switch 122 is mounted so as to havea contact finger 124 disposed in the path of an original sheet as thelatter is fed through the original sheet path by the roller pairs 110and 112. The switch 122 is suitably connected to the clutch solenoid 98by a lead 126 and to the severing mechanism solenoid 120 by a lead 128,so that these solenoids are energized when the switch 124 is closedduring the time that an original sheet is moving past the switch 122.During this time the feed rollers 72 and 74 are feeding a determinatelength of copy paper in accordance with the measured length of theoriginal sheet as determined by the sensing switch 122, and the cam gear66 is being rotated by the gear attached to the lower feed roller 76-.

In operation of the apparatus described above, a suitable master controlswitch energizes the motor 114 to drive the chain 24 in the directionindicated by the arrow. Simultaneously, all of the feed roller pairs inboth the original sheet path and the copy paper path are rotated insynchronism, with exception of the initial feed rollers 72 and 74.

If, now, an original sheet is introduced into the copying machinethrough the feed roller pair 110, the leading edge of the sheet deflectsthe finger 124 to close the switch 122, thereby energizing the clutchsolenoid 98 and the severing mechanism solenoid 120. The blade of thesevering mechanism is thereby retracted out of the path of the copysheet web, and simultaneously the copy paper feed clutch is engaged byrocking the lever to engage the gear 86 carried thereby with the gear 84carried by the shaft 76 of the feed roller 72, thereby causing rotationof the roller 72. The drive from the roller 72 is transferred to theupper roller 74 through the gears 80 and 82, thereby feeding copy paperfrom the supply roll 130, suitably mounted in the copying machine, tothe copy paper transfer mechanism whereby the copy paper is conveyedthrough the copying machine to be subjected to the various steps of thecopying process. One of these steps is that the copy paper is conveyedthrough the developing tank 20 in which the toner material adheres tothe electrostatically charged areas of the copy sheet as describedabove.

When the trailing edge of the original sheet passes the finger 124, theswitch 122 opens to cause disengagement of the feed clutch as well asactuation of the severing mechanism, whereby a length of copy sheet willhave been severed from the. web which corresponds to the length of theoriginal sheet. Thus, it will now be understood that the switch 122, theclutch elements and feed rollers 72 and 74 and the severing mechanism118 all constitute the means for feeding copy paper of varying lengthsto the copy paper transfer means.

While the feed rollers 72 and 74 are operating to feed copy paper, thegear 80 drives the cam gear 66 to rotate the cam 60 in the direction ofthe arrow ,in FIG. 1. When the cam follower 58 drops off the lobedportion 62 of the cam, the spring 70 causes the lever 56 to rock in aclockwise direction, thereby rotating shaft 52 and rocking the pumpactuator 50 in the same direction to depress the pump actuating stem 38,the latter causing a predetermined quantity of concentrated tonermaterial to be discharged from the spout 40 into the tube 42 and then tothe tank 20. Continued rotation of the cam 60 allows the spring 70 tomaintain the above parts in the just described position until the lo'bedportion 62 again raises the cam follower 58, the lever 56, and the pumpactuator 50, whereupon the spring in the pump, as is well known in theart, raises the pump actuating stem 38 and reprimes the pump preparatoryto another dispensing stroke of the actuating stem 38.

Preferably, but not necessarily, the size of the cam 60 is correlatedwith an average unit length of copy paper utilized over an extendedperiod of time. Thus, the cam 60 is preferably constructed to cause anactuation of the pump 34 each time 11 inches of copy paper is fed by therollers 72 and 74. It is apparent that this unit length may be varied tosuit particular circumstances, particularly where material to be copiedis of such a nature that the demand for toner replacement either exceedsor is less than the maximum and minimum limits of a pump adjustmentmechanism now to be described.

Referring to FIGS. 1 and 2, the shaft 52 carries an abutment member 132which is adapted to engage an adjustable stop 134 in the form of a thumbscrew threadedly engaged in a collar 136 secured to a cross-member 138of the copying machine. Adjustment of the thumb screw 134 limits therotation of the shaft 52 by the spring 70 and hence the downwardmovement of the pump actuating stem 38 on its dispensing stroke. In thismanner the quantity of toner material dispensed with each actuation ofthe pump can be varied from the maximum capacity of the pump to anylesser quantity desired in accordance with the extent of the indicia tobe copied per unit length of copy paper. The arrangement of the cam 60and cam follower 58 and the spring 70 thus constitute a lost motionconnection between the cam and the lever 50 for permitting variations ofthe toner quantity dispensed with each cycle.

While, for purposes of illustration, and as the embodiment at presentpreferred, the dispensing apparatus of the present invention has beendisclosed in combination with a copying machine of the type which feedsa variable length of copy paper from a web, the invention has equalapplicability in a copying machine which utilizes copy paper in sheetspre-cut to a predetermined length. Thus the variable length of copypaper fed for each copy is determined by the length of cut sheetsprovided in the machine, which of course, may vary from sheet to sheet.

In the above connection, the feed rollers 72 and 74 are controlled bysuitable means to operate for a period of time necessary to feed a cutsheet of known length. Such control may be either automatic by sensing achange of position of the copy sheet or by manually selectable means fora plurality of different lengths of copy sheet. In any event, theduration of operation of the feed rollers, corresponding to the lengthof time necessary to feed a sheet of predetermined length, controls theduration of operation of the pump actuating means, including the cam 60,so that the pump will still be actuated to dispense a metered quantityof toner material in response to the feeding of each predetermined unitlength of copy paper to and through the developing bath, notwithstandingthat the length of copy paper fed with each cycle of operation is nowpredetermined for any individual copy.

It will be apparent from the foregoing that there is disclosed a tonerdispensing apparatus for an electrophotographic copying machine whichachieves the foregoing objects. It is to be understood that theinvention is not to be limited to the specific embodiment describedabove and shown in the accompanying drawings, which embodiment is merelythe best mode presently contemplated for carrying out the principles ofthe invention and is susceptible to change in form, size, location andarrangement of parts, but rather the invention is intended to cover allsuch variations, modifications and equivalents thereof as may be deemedto be within the spirit and scope of the invention as defined in theappended claims.

We claim:

1. In combination with an electrophotographic copying machine havingmeans for feeding copy paper of varying lengths along a copy paper pathand including a feeding mechanism operable only when feeding one of saidvarying lengths of copy paper, and means for producing a visible imageon the copy paper from an original sheet, said means includingdeveloping means disposed in said path and having toner materialtherein, apparatus for automatically replacing an equivalent amount oftoner material as that withdrawn from the developing means each of saidlengths of copy paper passing therethrough, said apparatus comprising(A) supply means mounted in said copying machine providing a source ofconcentrated toner material,

(B) dispensing means having communication with said source of tonermaterial and with said developing means and operable when actuated todispense a metered quantity of toner material into said developingmeans,

(C) cyclically operable means for periodically actuating said dispensingmeans to dispense said metered quantity of toner material spaced inaccordance with the feeding of each predetermined unit length of thecopy paper by said feeding mechanism,

(D) means mechanically coupling said cyclically operable means to saidfeeding mechanism for operation therewith whereby the toner material isreplaced in said developing means at a rate which is correlated with therate at which the toner material is withdrawn from the developing meansby the varying lengths of copy paper passing therethrough,

(B) said dispensing means including a movable discharge element and saidcyclically operable means comprising a movable actuator for moving saiddischarge element and cam and cam follower means mechanically connectedto said actuator for moving the latter to cause operation of saiddischarge element, said coupling means driving said cam in response tooperation of said copy paper feeding mechanism, and

(F) said dispensing means comprises a positive displacement pump havinga reciprocating discharge element movable over a dispensing stroke and apriming stroke and resilient means normally urging said dischargeelement toward a terminal position of said priming stroke, and saidcyclically operable means comprises a movable actuator for moving saiddischarge element toward the terminal position of said dispensing strokewith sufficient force to overcome the force of said first namedresilient means, and cam and cam follower means connected tosaidactuator for moving the latter in a direction against the force of saidsecond named resilient means to permit said first named resilient meansand said discharge element to prime said pump before said second namedresilient means causes a dispensing stroke of said discharge element,and means for driving said cam in response to operation of said copypaper feeding means.

2. Apparatus according to claim 1 further including adjustable stopmeans interposed in the path of movement of said actuator in thedirection of movement caused by said second named resilient meanswhereby the extent of movement of said discharge element on saiddispensing stroke may be adjusted to vary the quantity of toner materialdispensed by said pump.

3. In combination with an electrophotographic copying machine havingmeans for feeding an original sheet through the copying machine, meansfor feeding copy paper along a copy paper path and including a feedingmechanism operable only when feeding one of said varying lengths of copypaper, and means for producing a visible image on the copy paper fromthe original sheet, said means including developing means disposed insaid path and having toner material therein, apparatus for automaticallyreplacing an equivalent amount of toner material as that withdrawn fromthe developing means by each of said lengths of copy paper passingtherethrough, said apparatus comprising (A) supply means mounted in saidcopying machine providing a source of concentrated toner material,

(B) dispensing means having communication with said source of tonermaterial and with said developing means and operable when actuated todispense a metered quantity of toner material into said developingmeans,

(C) cyclically operable means for periodically actuating said dispensingmeans to dispense said metered quan tity of toner material spaced inaccordance with the feeding of each predetermined unit length of copypaper by said feeding mechanism.

(D) means mechanically coupling said cyclically operable means to saidfeeding mechanism for operation therewith, and

(E) control means for determining the length of time said feedingmechanism is operative to feed copy paper and to cause operation of saidcyclically operable means whereby toner material is replaced in saiddeveloping means at a rate which is correlated with the rate at whichthe toner material is withdrawn from the developing means by the varyinglengths of copy paper passing therethrough, said control means includingsensing means for detecting the passage of an original sheet through thecopying machine, and means responsive to operation of said sensing meansfor respectively enabling and disabling said copy paper feedingmechanism in-accordance with the movement of the original sheet pastsaid sensing means whereby said feeding mechanism and said cyclicallyoperable means are simultaneously operated in accordance with themeasured length of the original sheet.

4. In combination with an electrophotographic copying machine havingmeans for feeding copy paper of varying lengths along a copy paper pathand including a feeding mechanism operable only when feeding one of saidvarying lengths of copy paper, and means for producing a visible imageon the copy paper from an original sheet,

said means including developing means disposed in said path and havingtoner material therein, apparatus for automatically replacing anequivalent amount of toner material as that withdrawn from thedeveloping means each of said lengths of copy paper passingtherethrough, said apparatus comprising (A) supply means mounted in saidcopying machine providing a source of concentrated toner material,

(B) dispensing means having communication with said source of tonermaterial and with said developing means and operable when actuated todispense a metered quantity of toner material into said developingmeans,

(C) cyclically operable means for periodically actuating said dispensingmeans to dispense said metered quantity of toner material spaced inaccordance with the feeding of each predetermined unit length of thecopy paper by said feeding mechanism,

(D) means mechanically coupling said cyclically operable means to saidfeeding mechanism for operation therewith whereby the toner material isreplaced in said developing means at a rate which is correlated with therate at which the toner material is withdrawn from the developing meansby the varying lengths of copy paper passing therethrough,

(B) said dispensing means including a movable discharge element and saidcyclically operable means comprising a movable actuator for moving saiddischarge element and cam and cam follower means mechanically connectedto said actuator for moving the latter to cause operation of saiddischarge element, said coupling means driving said cam in response tooperation of said copy paper feeding mechanism, and

(F) said cyclically operable means includes lost motion connection meansbetween said cyclically operable means and said dispensing means forvarying the actuating effect of said cyclically operable means on saiddispensing means whereby said metered quantity of toner materialdispensed with each actuation of said dispensing means may be varied.

References Cited UNITED STATES PATENTS 3,195,430 7/1965 Young 951.73,333,566 8/1967 Kent 951.7 X 3,354,802 11/1967 Doucette 95-1.7

I OHN M. HORAN, Primary Examiner US. Cl. X.R. 118637

